Mineral fertilization with macronutrients in castor bean, lineage UFRB 222
ABSTRACT The study was conducted to evaluate the effect of mineral fertilization on the growth and production of seeds and oil of castor bean (Ricinus communis L.) lineage UFRB 222. The experiment was carried out in a greenhouse of the Centro de Tecnologia e Recursos Naturais at the Universidade Federal de Campina Grande, PB, Brazil. A randomized block design with three repetitions and 14 treatments originated from a Baconian matrix was adopted. Reference doses were 50:300:150 kg ha-1 of N, P2O5 and K2O. At the end of the study, plant height, stem diameter, number of leaves, leaf area, total seed number, total seed weight, total fruit number and oil production per plant were evaluated. On average, the nitrogen dose of 150 kg ha-1 led to adequate values of growth and yield variables. For plant growth, 300 kg ha-1 of phosphorus should be applied, since the differences in the increase of growth variables between this dose and the highest ones estimated by the equations were very small; for castor bean production, the best applied dose was 600 kg ha-1 of phosphorus. The application of potassium increased the leaf area, number of seeds and production of oil, and the best dose was 300 kg ha-1. Phosphorus was the nutrient that promoted the highest production of oil per plant (92.40 g), followed by nitrogen (75.55 g) and potassium (72.10 g).